I need to compile AliRoot with the same defaults as O2 to use both at the same time, but it fails because cmake complains that alien is missing. It seems this request has been introduced in the first commit of PR #889 and it is enough to comment the line 213 of FindROOT.cmake to make AliRoot compile again. (This line issue a FATAL if alien is missing).
Is there a particular reason to enforce AliRoot to be compiled with alien? Otherwise, would it be possible to remove the request for alien in FindROOT.cmake?